At the woodworking show in Indy this weekend, I saw a Sand-Flee drum
sander, and a similar kit from a Canadian company called Stockroom
supply (https://www.stockroomsupply.com/VSander.asp).

I was impressed by the simplicity of these machines and the fact they
don't kick up a lot of dust. For the dust they do generate, you can
easily attach a shop-vac to gather it.

As I watched the demonstrations, I was thinking maybe this could be used
in place of a jointer to get one face and one edge flat to reference on
the planer and table saw rip fence. Seems like with a good flat table
(such as 3/4 MDF with a laminate) and a fence, it should do the same job
as a jointer. Also seems like it'd be safer since spinning sandpaper
would give you a little scuff but not lop off fingers.

I talked to Kelly Mehler about it after one of his demos. He said I
still needed a jointer, although he admitted he didn't have any
experience with the Sand-Flee/V-drum sanders. I respect Kelly and enjoy
his tablesaw book and DVD, but really wanted to know more about why I
need a jointer over a setup like this.

Other than speed, are there other things a jointer would give me that
would make it a better choice? I'm mainly thinking in terms of
dimensioning rough lumber.